Industrial robot with portable emergency stop unit

ABSTRACT

An industrial robot including a manipulator, a control unit for controlling the manipulator, a portable operating unit for teaching and manually operating the robot, which operating unit is adapted for wireless communication with the control unit, and an emergency stop unit. The emergency stop unit is arranged movable and the portable operating unit includes a first receiving member for receiving the emergency stop unit.

FIELD OF THE INVENTION

The present invention relates to an industrial robot comprising amanipulator, a control unit for controlling the manipulator, a portableoperating unit for teaching and manually operating the robot, whichoperating unit is adapted for wireless communication with the controlunit, and an emergency stop unit for stopping the manipulator uponactivating it.

The present invention also relates to an industrial robot systemcomprising a plurality of industrial robots, each having a manipulator,a control unit for controlling the manipulator and an emergency stopunit for stopping the manipulator upon activating it, and at least oneportable operating unit for teaching and programming the robots, whichportable operating unit is adapted for wireless communication with thecontrol units.

The present invention further relates to a portable operating unit foran industrial robot having a manipulator and a control unit forcontrolling the manipulator, the operating unit comprising means formanually operating the robot and means for wireless communicating withthe control unit.

The present invention further relates to a method for controlling thefunctioning of an emergency stop unit for an industrial robot comprisinga manipulator, a control unit for controlling the manipulator, and aportable operating unit for teaching and manually operating the robot,which portable operating unit is adapted for wireless communication withthe control unit.

The invention also relates to the use of an industrial robot foroperation control of a spot welding station.

A portable operating unit is generally denoted a teach pendant, and isused for manually controlling the robot, for example to teach or programthe robot to follow an operating path.

PRIOR ART

Robots are used to carry out repetitious and precise tasks, such aswelding and painting of components. The robots are programmed to carryout a work or a work cycle along an operating path. In order to programor teach the robot its working cycle, the robot is manipulated tovarious positions along the desired operating path. These positions arestored as instructions in a memory in the control unit. Otherinformation, such as desired robot movement velocity, may also be storedin the memory. During operation of the robot, the program instructionsare executed, thereby making the robot operate as desired.

Various devices used to facilitate the programming of robots are knownin the art. For example U.S. Pat. No. 4,888,708 issued to Brantmark etal discloses a portable teach pendant, for teaching and manuallyoperating the robot, by use of a joystick, a keyboard, and a visualdisplay unit. The keyboard has various function keys which permit anoperator to select different states for the control system. The teachpendant may for example be used for monitoring the robot program,changing certain variables in the program, starting, stopping andediting the program, and for manually moving the manipulator by use ofthe joystick. The operator is teaching the robot while watching themotion of the manipulator.

A robot can be operated in at least two modes: automatic and manual. Thechoice of mode, in which the robot shall operate, is made by switching amode selector key on a control panel on the control unit. When the robotis in the manual mode, the teach pendant has the exclusive right tooperate the robot and thus no other operating units are allowed tocontrol the robot. When the robot is in the automatic mode, some of thefunctions in the teach pendant are blocked, for example the functioningof the joystick.

The teach pendant disclosed in the above mentioned U.S. patent isconnected to the control unit via a flexible cable or wire. There aremany problems related to having a cable between the control unit and theteach pendant, particularly when there are several robots arranged neareach other in a robot line. The cable between the teach pendant and thecontrol unit has to be rather long and the risk for twisting the cablesof the robots is considerable. Neighboring robots could also have theircables twisted with each other and thus it is sometimes difficult toknow to which robot a certain teach pendant belongs. There is also arisk for breakage of the cables resulting in loss of communicationbetween the teach pendant and the control unit.

From the German patent No. DE 195 36 293 it is known to use a wirelesslink for exchange of information between the teach pendant and therobot. One advantage with a wireless connection between the robot andthe teach pendant is the possibility of using the same teach pendant forseveral robots. Accordingly, the teach pendant does not belong to acertain robot, and may be used together with any of the robots in arobot cell.

Robots are usually placed in robot cells in order to facilitate theautomation of a complex series of actions. When one of the robots in arobot cell is to be placed under manual control using a wireless teachpendant, it is important that the teach pendant is communicating withand controlling the correct robot. It must be possible to ensure correctassociation between the wireless teach pendant and the control unit.Otherwise, there is a risk for personal injury, should the operatorbelieve that he is operating a certain robot but is instead operatinganother robot in the cell. Thus, a problem arising when using a teachpendant not physically connected with the robot, is how to ensure thatthe correct robot is connected with the teach pendant.

Another problem with wireless communication between the robot and theteach pendant is the functioning of the emergency stop button on theteach pendant when the teach pendent is not connected with any robot.For safety reasons it is required that a visible emergency stop buttonstops the robot at any time the button is pushed. Accordingly, the teachpendant is not allowed to have a visible emergency stop button when itis not connected to any of the robots.

SUMMARY OF THE INVENTION

The object of the present invention is to provide an industrial robothaving a wireless operating unit which overcomes the problems mentionedabove and in particular the problem in connection with the functioningof the emergency stop button.

This object is achieved by means of the initially defined industrialrobot, characterised in that said emergency stop unit is arrangedmovable and the portable operating unit comprises a first receivingmember for receiving the emergency stop unit. Preferably, the emergencystop unit comprises an emergency stop button. Such movable emergencystop unit makes it possible to remove the emergency stop button from theoperating unit, when the operating unit is not connected to any robot,and then return the emergency stop button to the operating unit when theoperating unit is connected to a robot. Accordingly, it is ensured thatif the operating unit has a visible emergency stop button, the emergencystop button will function.

According to an embodiment of the invention, the robot comprises asecond receiving member for receiving the emergency stop unit, arrangedat or in connection with the control unit. Preferably, the control unitcomprises means for sensing the presence of the emergency stop unit andmeans for enabling the emergency stop unit upon presence in the secondreceiving member and the portable operating unit comprises means forsensing the presence of the emergency stop unit and means for enablingthe emergency stop unit upon presence in the operating unit. For safetyreasons, it is important that the emergency stop button always works,even when it is not used in the operating unit. To ensure that theemergency stop button always functions, the emergency stop button ismoved to a second receiving member in connection with the control unitwhen it is not used in the operating unit. The emergency stop button isenabled when the emergency stop unit has been received, either by thefirst receiving member or by the second receiving member.

According to a further embodiment of the invention, said movableemergency stop unit comprises means for carrying information about theidentity of the robot, and the portable operating unit comprises meansfor reading the robot identity from the emergency stop unit. To ensurethat the emergency stop button on the operator unit, upon activation,deactivates the correct robot, an identification of the robot istransmitted to the operating unit together with the movable emergencybutton. Accordingly, it is possible to ensure correct associationbetween the wireless operating unit and the control unit of the robotand the risk for emergency stopping the wrong robot is reduced.

According to a further embodiment of the invention the control unitcomprises means for comparing the identity of the robot with theidentity carried by the emergency stop unit and determining whether theidentities are equal. A problem associated with having a movableemergency stop unit is the risk for returning the emergency stop unit tothe wrong robot. This problem is solved by providing the control unitwith means for checking the identity of a received emergency stop unit.

According to a further embodiment of the invention the portableoperating unit comprises means for establishing a communication with thecontrol unit of the identified robot. A communication between theoperating unit and the control unit of a robot cannot be establisheduntil the operating unit has received information about the identity ofthe robot, to which it shall be associated. Since the identification ofthe robot is transferred together with the emergency stop unit, nocommunication could be established until the emergency stop unit ispresent in the operating unit. Thus, the operating unit is not able tocontrol the robot if the emergency stop button is not present. When acommunication is established with the control unit, the control unitknows that the operating unit has received the emergency stop button.

According to a further embodiment of the invention, the communicationbetween the portable operating unit and the control unit is carried outvia a base station and the movable emergency stop unit comprises meansfor carrying information about the address of the base station. Tofacilitate the establishment of the communication between the portableoperating unit and the control unit, the address of the base station istransferred to the operating unit through the emergency stop unit. For arobot cell, having several robots connected to a base station, thenumber of emergency stop units could be the same as the number of robotsin the cell. The emergency stop units will all have the same basestation address, but different robot identities.

According to a further embodiment of the invention the control unitcomprises means for measuring the time elapsed between the point of timewhen the emergency stop unit is removed from the second receiving memberuntil a communication is established between the portable operating unitand the control unit. Preferably, the control unit comprises means forcomparing said time with a predetermined maximum time and activating theemergency stop unit depending on the result of said comparison. For thepurpose of detecting a loss of the emergency stop unit, a timer isstarted upon removal of the emergency stop unit from the control unit.The timer is stopped when the emergency stop unit is received by theoperating unit and the communication is established. If the time exceedsa predetermined maximum time, an emergency stop of the robot isexecuted.

According to a further embodiment of the invention, the movableemergency stop unit comprises an electronic hardware device, for examplean information storage device. According to a further embodiment of theinvention, the movable emergency stop unit comprises a processor.

According to a further embodiment of the invention, the control unitcomprises means for detecting lack of robot identity in the emergencystop unit and means for transferring the identity of the robot to theemergency stop unit. Preferably, the control unit also comprises meansfor detecting lack of robot identity in the control unit itself andmeans for transferring the identity of the robot from the emergency stopunit to the control unit.

A further object of the invention is to provide an industrial robotsystem having a plurality of robots and at least one wireless operatingunit which could operate anyone of the robots, if correctly associatedwith it, which robot system overcomes the problems mentioned above andin particular the problem in connection with the functioning of theemergency stop button.

Another object of the invention is to provide a wireless portableoperating unit overcoming the problem in connection with the functioningof the emergency stop button.

Another object of the invention is to provide a method for ensuring thefunctioning of an emergency stop unit for an industrial robot.

Many of the above mentioned means are effectuated by softwareinstruction run on a processor in the operating unit or on a processorin the control unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained more closely by the description ofdifferent embodiments thereof and with reference to the appendeddrawings.

FIG. 1 is a perspective view of an industrial robot according to oneembodiment of the invention, comprising an operating unit adapted forwireless communication with a control unit of the robot.

FIG. 2 is a block diagram of the operating unit according to oneembodiment of the invention.

FIG. 3 is a block diagram of the control unit of an industrial robotaccording to one embodiment of the invention.

FIG. 4 shows an industrial robot system according to one embodiment ofthe invention, comprising an operating unit in wireless communicationwith the robots.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1 shows an industrial robot according to the invention, comprisinga portable operating unit 1 and a control unit 2 coupled fortransmitting data via a communication cable or a link to a manipulator3. The operating unit and the control unit are adapted for radiocommunication with each other. The control unit 2 is capable ofreceiving, processing and outputting data sent to it from the operatingunit. The operating unit 1 comprises a body 4, a display screen 5 and aset of function keys 6, and a joystick 7. The function keys 6 permit anoperator to select various states for the control system. The joystickis used for controlling the movement of the manipulator when the robotis manually operated and could be used as a mouse. The operating unit 1further comprises an antenna 9 for radio communication with the controlunit 2 and an opening 8 adapted for receiving a movable emergency stopunit 10. The control unit 2 comprises an operator panel 13 having keysfor setting the control unit, an emergency stop button 14 and an opening15 adapted for receiving the movable emergency stop unit 10.

FIG. 2 shows the operating unit 1 having received the movable emergencystop unit 10. At least a part of the emergency stop unit 10 is insertedinto the opening 8. The emergency stop unit 10 includes an emergencystop button 11 and contact elements 12 adapted for being in electricalcontact with corresponding contact elements 20 on a receiving member 21positioned inside the operating unit 1. The emergency stop unit 10further comprises an electronic hardware device 22 including a memory ora register adapted for storing information about the identity of therobot, to which the emergency stop unit belongs. The receiving member 21is adapted for sensing the presence of the emergency stop unit 10 in theoperating unit and reading information about the robot identity from thehardware device 22 to a data bus 23. The robot is arranged so that, thepower supply to the manipulator is broken upon pushing the emergencystop button 11. When the emergency stop unit 10 is received in theoperating unit 1, the button 11 is enabled and will trigger an emergencystop if activated. The enabling of the emergency stop button iseffectuated by software instruction run on the processor unit 24.

When the operating unit 1 has received the emergency stop unit 10, thecontact elements 12 of the emergency stop unit 10 and the contactelements 20 of the receiving member 21 are in electrical contact witheach other. Information about the identity of the robot is transmittedfrom the hardware device 22 to the data bus 23 by the receiving member21. The operating unit 1 further comprises a processing unit 24 adaptedfor processing data programs for controlling the function of theoperating unit, a memory 25 for storing the data programs and theinformation about the robot identity, interface means 26 for couplinginput and output signals between the data bus 23 and the display screen5, the function keys 6 and the joystick 7, and a coupling element 27 forconverting and coupling data between the antenna 9 and the data bus 23.

FIG. 3 shows the control unit 2 having received the movable emergencystop unit 10. At least a part of the emergency stop unit 10 is insertedinto the opening 15. The contact elements 12 of the emergency stop unit10 are adapted for being in electrical contact with correspondingcontact elements 30 on a receiving member 31 positioned inside thecontrol unit. The receiving member 31 is adapted for sensing thepresence of the emergency stop unit 10 in the control unit 2 and readingthe information about the robot identity from the hardware device 22 inthe emergency stop unit 10 to the data bus 32. The control unit 1further comprises a processing unit 33, a memory 34 for storing dataprograms and parameters, a first interface means 35 for transmittinginput and output signals between the data bus 32 and the operator panel13, a coupling element 36 for converting and coupling data between anantenna 39 and the data bus 32, and a second interface means 38 fortransmitting data and control signals between the data bus 32 and themanipulator. The control unit 1 also includes a timer unit 37, discussedbelow.

When the emergency stop unit 10 is received by the control unit 2, theemergency stop button 11 is enabled, i.e. upon pushing the emergencystop button 11 the power supply to the manipulator is broken. Theenabling of the emergency stop button is effectuated by softwareinstruction run on the processor unit 33. Thus, the control unit has twoworking emergency stop buttons 10, 14. The control unit needs twoemergency stop buttons for ensuring that it always is provided with astop button, even though one of them is moved to the operating unit.

When the operating unit 1 is not used, the emergency stop unit 10 ispositioned at the control unit 2. If an operator decides to use theoperating unit, he moves the emergency stop unit 10 to the operatingunit 1. The receiving member 21 senses the presence of the emergencystop unit 10 and reads the information about the robot identity from thehardware device 22 and transmits it, via the data bus 23, to theprocessor unit 24. When the processor unit has received the informationabout the robot identity, it establishes a radio contact with thecontrol unit 2 of the identified robot, via the coupling element 27 andthe antenna 9.

When the operating unit 1 is not to be used, the emergency stop unit 10is returned to the control unit 2 and remains there until the next timethe operating unit 1 is to be used. When the receiving member 31 in thecontrol unit has sensed the presence of the emergency stop unit 10, ittransmits the information about the robot identity from the hardwaredevice 22, via the data bus 32, to the processor unit 33. When theprocessor unit 33 has received the information about the robot identity,it compares it with a stored robot identity, for the purpose of checkingthat the received emergency stop unit is the correct one, belonging tothe robot. If the identities are not the same, the control unit will notaccept receiving the emergency stop unit and will generate an alarmsignal.

For the purpose of detecting a loss of the emergency stop unit 10, thetimer unit 37 is started when the emergency stop unit 10 is removed fromthe control unit 2 and is stopped when the emergency stop button isreceived by the operating unit 1 and the communication is established.When the timer runs out, i.e. when the time elapsed exceeds apredetermined maximum value, an emergency stop is executed or any otheraction is taken.

The robot may be operated in an automatic or a manual mode. Normally,the robot is in the automatic mode during work and in the manual modeduring teaching. In an embodiment of the invention, the switchingbetween the automatic and the manual mode could be effected by movingthe emergency stop unit from the control unit to the operating unit andvice versa. Accordingly, upon sensing the presence of the emergency stopunit in the control unit, the robot is operated in automatic mode, i.e.the robot is under automatic control, and upon sensing the presence ofthe emergency stop unit in the operating unit, the robot is operated inthe manual mode, i.e. the robot is controlled by the operating unit.

FIG. 4 shows a robot cell having six robots, each comprising amanipulator 3 a-3 f and a control unit 2 a-2 f. Each robot can becontrolled via a portable operating unit 1. The control units 2 a-2 fand the operating unit 1 are adapted for being in radio communicationwith each other via a base station 40. For activating the operating unit1 it needs to have the address to the base station 40 and the identityof the robot to which it shall be connected. This is done by moving themovable emergency stop unit from the selected robot to the operatingunit. Beside the robot identity, the hardware unit 22 comprises theaddress to the base station. The robot identity includes the networkaddress of the robot to be controlled by the operating unit. The sixemergency stop units 10 a-10 f have the same base station address butdifferent robot identities. In the example shown in FIG. 4, the robotcomprising controller 2 d is selected for being controlled by theoperating unit 1. Thus, the emergency stop button 10 d is moved to theoperating unit 1.

Each of the robots in the cell has an emergency stop unit. If the cellcomprises more than one operating unit 1, the emergency stop units canbe used in any of the operating units, but the control units will onlyaccept one unique emergency stop unit. The linking between a robot andan operating unit is done by use of the movable emergency stop button.Any number of operating units can be active in the cell, but the onlyoperating unit able to manipulate the robot is the one in possession ofits emergency stop button.

Upon return of the emergency stop unit 10 d to the control unit 2 d, theoperating unit 1 will send a message to the control unit informing itabout the fact that the emergency stop unit has been removed from theoperating unit. This will stop the manipulator and start the timer inthe control unit. The timer is stopped when the control unit hasreceived the emergency stop unit. If the transfer time exceeds apredetermined value, the emergency stop will be activated. If it is notpossible to communicate with the control unit when the emergency stopunit is removed from the operating unit, the manipulator is stopped fromthe moment the communication is broken, until the control unit hasreceived the emergency stop unit.

As long as the emergency stop unit is not present in the control unit,the communication with the operating unit is supervised and the controlunit will emergency stop the robot if the communication is broken andthe emergency stop unit is not returned within a predetermined timeinterval. The communication can for example be broken if the operatingunit leaves the radio coverage area. Thus, if the emergency stop unit isstill in the operating unit when the operating unit leaves the radiocoverage area, the robot will be emergency stopped.

For safety reasons it is sometimes desirable to emergency stop some, orall of the robots in a robot cell or in the same working area, uponactivation of the emergency stop button on the operating unit.Accordingly, in an embodiment of the invention the emergency stop unitis adapted for comprising further information about identities of robotswhich shall be emergency stopped at the same time upon activation of theemergency stop button.

In another embodiment of the invention, the emergency stop unitcomprises a first part fixedly arranged in the control unit and a secondmovable part. The second movable part is used for message encryption andthe first part is used for message decryption.

The present invention is not limited to the embodiments disclosed butmay be varied and modified within the scope of the following claims. Forexample, the means for carrying information about the identity of therobot could be implemented in a number of different ways, such as aphysical key device, magnetic means, or visible information. The meansfor reading the robot identity from the emergency stop unit could forexample be a mechanical, magnetic or optical reading means. Theelectronic hardware device in the emergency stop unit is preferablycomprising a processor and software instructions.

1. An industrial robot, comprising: a manipulator; a movable emergencystop unit comprising an emergency stop button configured when enabled totrigger an emergency stop of the manipulator upon activation; a controlunit for controlling the manipulator, the control unit comprising afirst receiving member configured to receive the emergency stop unit,the control unit further comprising a sensor configured to detect thepresence of the emergency stop button in the first receiving member anda processor configured to enable the emergency stop button upondetecting the presence of the emergency stop unit in the first receivingmember; and a portable operating unit for teaching and manuallyoperating the robot, the portable operating unit comprising a secondreceiving member configured to receive the emergency stop unit removedfrom the control unit, the portable operating unit further comprising asensor configured to detect the presence of the emergency stop button inthe second receiving member and a processor configured to enable theemergency stop button and establish wireless communication with thecontrol unit upon detecting the presence of the emergency stop unit inthe second receiving member, wherein the emergency stop unit is movableback and forth between the first receiving member of the control unitand the second receiving member of the portable operating unit.
 2. Theindustrial robot according to claim 1, wherein said movable emergencystop unit comprises means for carrying information about an identity ofthe robot and the portable operating unit comprises means for readingthe robot identity from the emergency stop unit.
 3. The industrial robotaccording to claim 1, wherein the control unit comprises means forcomparing an identity of the robot with an identity carried by theemergency stop unit and determining whether the identity of the robotand the identity carried by the emergency stop unit are equal.
 4. Theindustrial robot according to claim 1, wherein the communication betweenthe portable operating unit and the control unit is carried out via abase station and the movable emergency stop unit further comprises meansfor carrying information about the address of the base station.
 5. Theindustrial robot according to claim 1, wherein the control unit furthercomprises means for measuring a time elapsed between a point of timewhen the emergency stop unit is removed from the second receiving memberuntil when a wireless communication is established between the portableoperating unit and the control unit.
 6. The industrial robot accordingto claim 5, wherein the control unit further comprises means forcomparing said time with a predetermined maximum time and activating theemergency stop unit depending on the result of said comparison.
 7. Theindustrial robot according to claim 2, wherein the control unit furthercomprises means for detecting lack of robot identity in the emergencystop unit and means for transferring the identity of the robot to theemergency stop unit.
 8. The industrial robot according to claim 2,wherein the control unit further comprises means for detecting lack ofrobot identity in the control unit itself and means for transferring theidentity of the robot from the emergency stop unit to the control unit.9. The industrial robot according to claim 1, further comprising: a spotwelding apparatus.
 10. A method for ensuring the functioning of amovable emergency stop unit for an industrial robot comprising amanipulator, a movable emergency stop unit comprising an emergency stopbutton configured when enabled to trigger an emergency stop of themanipulator upon activation, a control unit for controlling themanipulator, the control unit comprising a first receiving memberconfigured to receive the emergency stop unit, the control unit furthercomprising a sensor configured to detect the presence of the emergencystop button in the first receiving member and a processor configured toenable the emergency stop button upon detecting the presence of theemergency stop unit in the first receiving member, a portable operatingunit for teaching and manually operating the robot, the portableoperating unit comprising a second receiving member configured toreceive the emergency stop unit removed from the control unit, theportable operating unit further comprising a sensor configured to detectthe presence of the emergency stop button in the second receiving memberand a processor configured to enable the emergency stop button andestablish wireless communication with the control unit upon detectingthe presence of the emergency stop unit in the second receiving member,the method comprising: moving the emergency stop unit from the secondreceiving member of the control unit to the first receiving member ofthe portable operating unit; detecting the presence of the emergencystop unit in the first receiving member of the portable operating unit;establishing wireless communication between the portable operating unitand the control unit; enabling the emergency stop unit in the firstreceiving member of the portable operating unit; and actuating theemergency stop unit to stop movement of the manipulator.
 11. The methodaccording to claim 10, further comprising: transmitting informationabout the identity of the robot from the emergency stop unit to theportable operating unit.
 12. The method according to claim 10, furthercomprising: measuring a time elapsed between a point of time when theemergency stop unit is being removed from the place at or in connectionwith the control unit until said communication is established betweenthe operating unit and the control unit.
 13. The method according toclaim 10, further comprising: moving the emergency stop unit from theoperating unit to said place at or in connection with the control unitand checking whether the received emergency stop unit carries the sameidentification as the robot connected to the control unit.
 14. Anindustrial robot system, comprising: a plurality of industrial robots,each robot comprising a manipulator; a movable emergency stop unitcomprising an emergency stop button configured when enabled to triggeran emergency stop of the manipulator upon activation, the emergency stopunit also configured to store information about an identity of the robotto which the emergency stop unit belongs; and a control unit forcontrolling the manipulator, the control unit comprising a firstreceiving member configured to receive the emergency stop unit, thecontrol unit further comprising a sensor configured to detect thepresence of the emergency stop button in the first receiving member anda processor configured to enable the emergency stop button upondetecting the presence of the emergency stop unit in the first receivingmember; a portable operating unit for teaching and manually operatingthe robots, the portable operating unit comprising a second receivingmember configured to receive the emergency stop unit removed from one ofthe control units, the portable operating unit further comprising asensor configured to detect the presence of the emergency stop button inthe second receiving member and a processor configured to read theidentity of the robot to which the emergency stop unit belong and toenable the emergency stop button and establish wireless communicationwith the control unit of the robot to which the emergency stop buttonbelongs upon detecting the presence of the emergency stop unit in thesecond receiving member.
 15. The industrial robot system according toclaim 14, wherein each of the robots comprises a processor configured todetermine whether the received emergency stop unit carries the sameidentification as the robot.
 16. The industrial robot according to claim14, wherein one of the robots further comprises a spot weldingapparatus.